As in previous years, the cardiopulmonary program is primarily concerned with the interplay between respiration and circulation in health and in disease. The research efforts fall into five distinct categories: the regulation of ventilation, the regulation of the circulation, the pathogenesis of arteriosclerosis, myocardial performance, and hemodynamics. There is an effective interplay among the various investigators so that techniques in one specialized area are quickly adapted for research and clinical purposes in other areas. For example, the development of new tests for determining the sensitivity of the respiratory center has led to screening methods which apply to the development of corpulmonale and heart failure. During the current year, new investigators have joined the program bringing new techniques and concepts which will be useful in developing the missions of the program with respect to research in cardiopulmonary disease.